According to the prior art, this type of sonar consists, as represented in FIG. 1, of a cylindrical antenna formed by a support 10 on which columns of transducers 11 are fitted. The transducers are generally of the “Tonpilz” type and carry out both transmission and reception. The antenna is fixed to the hull by using a piece 12 in which tapped holes 120 have been made.
For transmitted frequencies higher than several kHz, typically 5 kHz, such an antenna still has reasonable dimensions and weight. For lower frequencies, between 1 and 2 kHz for example, the antenna becomes too heavy. The quality-factor Q of the transducers furthermore limits the frequency band in this case.